Thermosetting low-dielectric resin composition and use thereof

ABSTRACT

A thermosetting low-dielectric resin composition which has a low dielectric constant and a low dielectric tangent for use in a printed circuit board and which has excellent adhesion to a metal and scatters almost no resin when used for forming a prepreg by punching or cutting, the composition comprising a component (a): siloxane-modified polyimide, component (b): a compound containing 2 methylallyl groups and having the following formula (1) or a compound containing 3 allyl groups or 3 methylallyl groups and having the following formula (1A), and component (c): a compound containing at least 2 maleimide groups,                    
     wherein R is a hydrogen atom or methyl group.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thermosetting low-dielectric resincomposition for print circuit board and its use. More specifically, itrelates to a thermosetting low-dielectric resin composition which has alow dielectric constant and a low dielectric tangent and which showsexcellent adhesion to metals and scatters almost no resin during workingand also relates to a laminated board, a metal-clad laminated board anda circuit laminate material to which the above resin composition isapplied.

2. Description of Prior Art

In recent years, remarkable increases are found in signal speeds andoperation frequency of electronic systems. For electronic systems foruse in a high-frequency region, it is desired to use a resin for alaminated board which has excellent heat resistance, a low dielectricconstant and a low dielectric tangent and a laminated board or ametal-clad laminate obtained from prepregs using a resin having theabove properties. A laminated board or a metal-clad laminate using alow-dielectric material enables higher-speed processing of signals sinceit can increase the propagation rate of electric signals.

It has been also proposed to use a fluorine resin and a polyphenyleneether resin which have low dielectric constants. However, these have aproblem that they are poor in workability and adhesion and lessreliable. For improving workability and adhesion, there has beenproposed an epoxy-modified polyphenylene ether resin or apolyphenylene-ether-modified epoxy resin. Since, however, an epoxy resinhas a high dielectric constant, satisfactory properties have not yetbeen obtained. There is known a curable resin composition prepared bymixing a polyphenylene ether resin, a polyfunctional cyanate ester resinand some other resin, adding a radical polymerization initiator andallowing the mixture to undergo a preliminary reaction (JP-A-57-185350),while the above resin composition is insufficient with regard to adecrease in dielectric constant.

Further, a polybutadiene resin containing a thermosetting1,2-polybutadiene as a main component has a low dielectric constant,while it is poor in adhesion and is insufficient in heat resistance.There has been proposed a composition containing 100 parts by weight ofa polyphenylene ether resin, 5 to 20 parts by weight of1,2-polybutadiene resin, 5 to 10 parts by weight of a crosslinkingmonomer and a radical crosslinking agent (JP-A-61-83224). When1,2-polybutadiene resin is used, however, sticking nature remains aftera solvent is removed, and the practical problem is that a prepregprepared by applying the above resin to a glass material or impregnatinga glass material with it cannot maintain a tack-free state. When a1,2-polybutadiene having a high molecular weight is used for removingthe sticking nature, there is a problem that it has a low solubility ina solvent so that a solution has an increased viscosity and shows adecreased fluidity.

There has been proposed a low-dielectric laminated board or copper-cladlaminate prepared by impregnating a fluorocarbon fiber fabric with athermosetting resin (JP-B-2578097). In this case, however, it isrequired to surface-treat the fluorocarbon fiber for improving theadhesion between the fluorocarbon fiber and the thermosetting resin, andthe laminated board or copper-clad laminate is very expensive since thefluorocarbon fiber is expensive, which results in difficulties inpractical use.

A multi-layered printed circuit board for use in an electronic machineor device has an electric circuit on an inner layer as well. Themulti-layered printed circuit board is fabricated by providing an innercircuit board on which a circuit is formed beforehand and copper foil(s)for outer-layer circuit(s), stacking the inner circuit board and thecopper foil(s) through prepreg, shaping the resultant set under heat andpressure to prepare a multi-layered copper-clad laminate having aninner-layer circuit, and forming circuit(s) on outer layer(s). As theabove prepreg, there is used a glass-cloth-substrate epoxy-resinprepreg. Since the signal speed and performance frequency of electronicmachines and devices remarkably increase in recent years, thin circuitlaminate materials having excellent heat resistance, a low dielectricconstant and a low dielectric tangent are desired for micro-wiring inelectronic machines and devices for use in a high-frequency region,particularly, electronic machines and devices which are required to bedownsized and decreased in weight. With a thin circuit laminate materialfrom a low-dielectric material, the propagation speed of electricsignals can be increased, so that signals can be processed at a higherspeed.

For a thin multi-layered printed circuit board, a thinglass-cloth-substrate epoxy-resin prepreg having a thickness of 30 to100 μm is used at present. However, fiber lines are liable to appear, anuneven surface of an inner-layer circuit substrate cannot be absorbedwithin the prepreg, and an uneven surface is liable to be formed as asurface of an outer-layer, so that the smoothness of the surface isimpaired, which is a bar against the formation of micro-wirings. Thereis therefore found a method in which the conventionalglass-cloth-substrate epoxy-resin prepreg is replaced with aglass-cloth-free adhesive film as a prepreg, or a method in which aresin-applied copper foil prepared by stacking an adhesive layer on onesurface of a copper foil for an outer-layer circuit beforehand is usedas both a copper for an outer-layer circuit and a prepreg. The aboveadhesive film and the above resin-applied copper foil use a resin havingfilm formability, and the resin that can be used is limited to thoseresin having film formability. When a resin having no film formabilityis used, the resin is liable to cause troubles such as breaking andchipping in the steps of transporting, cutting and laminating theadhesive film. Further, when the resin having no film formability isused as an insulating material for inter-layer connection of amulti-layered board, the inter-layer insulating layer is liable toextremely decreases in thickness in an inner-layer circuit presenceportion during shaping of a multi-layered board under heat and pressure,or it is liable to cause troubles such as a decrease in inter-layerinsulation resistance and a short circuit. As a resin having filmformability, there have been proposed a thermoplastic polyimide adhesivefilm (U.S. Pat. No. 4,543,295), a high-molecular-weight epoxy resin(JP-A-4-120135), an acrylonitrile-butadiene copolymer/phenolic resin(JP-A-4-29393), a phenolic resin/butyral resin (JP-A-4-36366) and anacrylonitrile-butadiene copolymer/epoxy resin (JP-A-4-41581). However,these resin have a problem on dielectric constant properties, and theyare not feasible for processing signals at a higher speed.

As a low-dielectric resin, there have been proposed a fluorine resin, apolyphenylene ether resin, a polybutadiene resin containingthermosetting 1,2-polybutadiene as a main component, and a compositioncontaining 100 parts by weight of a polyphenylene ether resin, 5 to 20parts by weight of 1,2-polybutadiene resin, 5 to 10 parts by weight of acrosslinking monomer and a radical crosslinking agent (JP-A-61-83224).However, these resin have difficulties in practical use since they arepoor in heat resistance, workability and film formability.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a thermosettingresin composition which has a low dielectric constant and a lowdielectric tangent for use in a printed circuit board and which hasexcellent adhesion to a metal and scatters almost no resin when aprepreg is prepared by punching or cutting.

It is another object of the present invention to provide a laminatedboard and a metal-clad laminate to which the above thermosetting resincomposition is applied.

It is still another object of the present invention to provide anadhesive film of a thermosetting low-dielectric resin composition whichhas a low dielectric constant and a low dielectric tangent for use in aprinted circuit board, which has excellent adhesion to a metal andscatters almost no resin when a prepreg is prepared by punching orcutting and which has film formability, or a metal foil to which theabove thermosetting resin composition is applied, the adhesive film orthe metal foil being a circuit laminate material.

According to the present invention, there is provided a thermosettingresin low-dielectric composition comprising a component (a):siloxane-modified polyimide, component (b): a compound containing 2methylallyl groups and having the following formula (1) or a compoundcontaining 3 allyl groups or 3 methylallyl groups and having thefollowing formula (1A), and component (c): a compound containing atleast 2 maleimide groups.

wherein R is a hydrogen atom or methyl group.

According to the present invention, further, the above thermosettinglow-dielectric resin composition includes an embodiment in which thetotal content of the components (b) and (c) per 100 parts by weight ofthe component (a) is 10 to 900 parts by weight and the content ofmethylallyl or allyl groups of the component (b) per mole equivalent ofmaleimide groups of the component (c) is 0.1 to 2.0 mol equivalent.

According to the present invention, further, the above thermosettinglow-dielectric resin composition includes an embodiment in which thesiloxane-modified polyimide as a component (a) contains 90 to 40 mol %of at least one of structural units of the following formula (2a) and 10to 60 mol % of at least one of structural units of the following formula(2b) when the component (b) is the compound of the formula (1).

wherein X is a tetravalent aromatic group and is any one of a3,3′,4,4′-diphenylsulfone structure, a 3,3′,4,4′-biphenyl structure and2,3′,3,4′-biphenyl structure, Ar is a divalent group selected fromaromatic-ring-possessing groups of the following formula (3), R is—CH₂OC₆H₄— whose methylene group is bonded to Si or an alkylene grouphaving 1 to 10 carbon atoms, and n is an integer of 1 to 20,

wherein each of R₁, R₂, R₃ and R₄ is independently a hydrogen atom or analkyl or alkoxy group having 1 to 4 carbon atoms provided that all ofthese are hydrogen atoms in no case.

According to the present invention, further, the above thermosettinglow-dielectric resin composition includes an embodiment in which thesiloxane-modified polyimide as a component (a) contains 90 to 40 mol %of at least one-of structural units of the following formula (2a′) and10 to 60 mol % of structural units of the following formula (2b′) whenthe component (b) has the formula (1A).

wherein X is a direct bond or any one of binding groups of —O—, —SO₂—,—CO—, —C(CH₃)₂—, —C(CF₃)₂— and —COOCH₂CH₂OCO—, Ar is a divalent groupselected from aromatic-ring-possessing groups of the following formula(3A), R is —CH₂OC₆H₄— whose methylene group is bonded to Si or analkylene group having 1 to 10 carbon atoms, and n is an integer of 1 to20,

wherein each of R₁, R₂, R₃ and R₄ is independently a hydrogen atom or analkyl or alkoxy group having 1 to 4 carbon atoms provided that all ofthese are hydrogen atoms in no case.

Further, according to the present invention, the above thermosettinglow-dielectric resin composition includes an embodiment in which thesiloxane-modified polyimide as a component (a) contains 90 to 40 mol %of at least one of structural units of the following formula (2a) and 10to 60 mol % of structural units of the following formula (2b) when thecomponent (b) has the formula (1A).

wherein X is a tetravalent aromatic group and is any one of a3,3′,4,4′-diphenylsulfone structure, a 3,3′,4,4′-biphenyl structure and2,3′,3,4′-biphenyl structure, Ar is a divalent group selected fromaromatic-ring-possessing groups of the following formula (3A), R is—CH₂OC₆H₄— whose methylene group is bonded to Si or an alkylene grouphaving 1 to 10 carbon atoms, and n is an integer of 1 to 20.

According to the present invention, further, there is provided athermosetting low-dielectric resin composition which shows a dielectricconstant of 3.2 or less after cured.

Further, according to the present invention, there is provided alaminated board comprising at least one prepreg sheet prepared byimpregnating a reinforcing fiber material with the above thermosettinglow-dielectric resin composition.

Further, according to the present invention, there is provided ametal-clad laminate comprising the above laminated board and a metalfoil or foils which is or are stacked on and integrated with one surfaceor both surfaces of the laminated board. In the present invention, themetal-clad laminate is used in a state where the thermosettinglow-dielectric resin composition is in a semi-cured state or a curedstate as required depending upon use.

Further, according to the present invention, there is provided a circuitlaminate material comprising either a peeling-off layer or a metal foiland the above thermosetting low-dielectric resin composition which islaminated on one surface of the peeling-off layer or the metal foil.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be explained in detail hereinafter.

First, the thermosetting low-dielectric resin composition of the presentinvention will be explained.

The thermosetting low-dielectric resin composition of the presentinvention comprises a component (a): siloxane-modified polyimide, acomponent (b): a compound containing at least 2 methylallyl groups andhaving the above formula (1) or a compound containing at least 3 allylor methylallyl groups and having the above formula (1A) and a component(c): a compound containing 2 maleimide groups.

The amount ratio of the above components (a) to (c) is as follows. Thetotal content of the components (b) and (c) per 100 parts by weight ofthe component (a) is 10 to 900 parts by weight, and the content of theallyl or methylallyl groups per mole equivalent of the maleimide groupsof the component (c) is 0.1 to 2.0 mole equivalents.

When the siloxane-modified polyimide is used, the resin composition isimproved in flexibility, the scattering of a resin during working isremarkably decreased, and the handling of the composition is eased whenprinted circuit boards are fabricated, so that the yield of the printedcircuit boards is improved.

The siloxane-modified polyimide used in the present inventionstructurally contains siloxane, and the modification ratio of thepolyimide with siloxane is 1 to 60 mol %. When the component (b) is acompound of the above formula (1), preferably, the siloxane-modifiedpolyimide contains 90 to 40 mol % of at least one of structural units ofthe above formula (2a) and 10 to 60 mol % of at least one of structuralunits of the above formula (2b).

When the component (b) is a compound of the above formula (1A),preferably, the siloxane-modified polyimide used in the presentinvention 90 to 40 mol % of at least one structural units of the aboveformula (2a′) and 10 to 60 mol % of at least one of structural units ofthe above formula (2b′). When the component (b) is a compound of theabove formula (1), preferably, the siloxane-modified polyimide contains90 to 40 mol % of at least one of structural units of the above formula(2a) and 10 to 60 mol % of at least one of structural units of the aboveformula (2b). Further preferably, the content of the structural units ofthe formula (2b) or (2b′) is 10 to 40 mol %.

Preferably, the siloxane-modified polyimide has a weight averagemolecular weight of 5,000 to 500,000, a glass transition temperature of150° C. or lower and a dielectric constant of 3.0 or lower. Morepreferably, the siloxane-modified polyimide has a weight averagemolecular weight of 5,000 to 300,000, a glass transition temperature of140° C. or lower and a dielectric constant of 3.0 or lower. Still morepreferably, the siloxane-modified polyimide has a weight averagemolecular weight of 10,000 to 300,000, a glass transition temperature of130° C. or lower and a dielectric constant of 3.0 or lower. When theabove weight average molecular weight is smaller than the above lowerlimit, undesirably, the resin composition shows poor thermal stabilityand consequently shows poor heat resistance. When the weight averagemolecular weight is larger than the above upper limit, undesirably, themelt viscosity of the resin composition increases so that the resincomposition is poor in workability and adhesion. When the above glasstransition temperature is higher than the above upper limit,undesirably, the melting temperature of the resin composition increasesso that the working temperature is caused to increase or the adhesion ispoor. When the above dielectric constant exceeds 3.0, undesirably, it isdifficult to prepare the resin composition having a low dielectricconstant.

In the present invention, the glass transition temperature refers to atemperature measured under the following conditions.

Conditions for measuring glass transition temperature (T_(g))

Apparatus: apparatus for measuring modulus of elasticity in shear (“RheoStress RS75” produced by HAAKE Co., Ltd.)

Measurement temperature range: from −10° C. to 300° C.

Temperature elevation rate: 3° C./minute

Measurement frequency: 1 Hz

Strain ratio: 0.01%±0.0025%

The siloxane-modified polyimide used in the present invention can beprepared by a general method used for producing a polyimide. That is,the siloxane-modified polyimide can be produced from tetracarboxylicacid dianhydride corresponding to recurring structural units and adiamine or diisocyanate corresponding to recurring structural units.

Specifically, the siloxane-modified polyimide can be produced byreacting a tetracarboxylic acid dianhydride, a compound having the aboveformula (3) or (3A) and a siloxane compound of the following formula(5).

wherein R is as defined in the above formula (2b) and Y is an aminogroup or an isocynato group.

The tetracarboxylic acid dianhydride includes pyromellitic aciddianhydride, 3,3′,4,4′-diphenylsulfone-tetracarboxylic acid dianhydride,3,3′,4,4′-benzophenonetetracarboxylic acid dianhydride,3,3′,4,4′-biphenyltetracarboxylic acid dianhydride,2,3′,3,4′-biphenyltetracarboxylic acid dianhydride,bis(3,4-dicarboxyphenyl)ether dianhydride,4,4′-bis(3,4-dicarboxyphenoxy)diphenylsulfone dianhydride, ethyleneglycol bistreimellitate dianhydride and2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride. Preferredare 3,3′,4,4′-diphenylsulfonetetracarboxylic acid dianhydride,3,3′,4,4′-biphenyltetracarboxylic acid dianhydride and2,3′,3,4′-biphenyltetracarboxylic acid dianhydride.

In the siloxane compound of the formula (5) used as a material for thepreparation of the polyimide, diamines of the formula (5) in which thefunctional group Y is an amino group includebis(3-aminopropyl)tetramethyldisiloxane,bis(10-aminodecamethylene)tetramethyldisiloxane, dimethylsiloxanetetramer or octamer having an aminopropyl terminal group, and bis(3-aminophenoxymethyl) tetramethyldisiloxane. These siloxane compoundsmay be used alone or in combination.

In the siloxane compound of the formula (5), isocyanates of the formula(5) in which the functional group Y is an isocyanato group include thoseformed by replacing “amino” of the above diamines with “isocyanato”.

In the siloxane compound of the above formula (5), isocyanates of theformula (5) in which the functional group Y is an isocyanate group canbe easily prepared by reacting the corresponding diamines describedabove as examples with phosgene according to a conventional method.

When the component (b) is a compound of the formula (1), preferably, thesiloxane-modified polyimide contains 90 to 40 mol % of at least one ofstructural units of the formula (2a) and 10 to 60 mol % of at least oneof structural units of the formula (2b). When the component (b) is acompound of the formula (1A), preferably, the siloxane-modifiedpolyimide contains 90 to 40 mol % of at least one of structural units ofthe formula (2a′) and 10 to 60 mol % of at least one of structural unitsof the formula (2b′). More specific examples of the diamines which canconstitute Ar in the formula (2a) or (2a′) are as follows.

1,3-bis[1-(3-aminophenyl)-1-methylethyl]benzene,1,3-bis[1-(4-aminophenyl)-1-methylethyl]benzene,1,4-bis[1-(3-aminophenyl)-1-methylethyl]benzene,1,4-bis[1-(4-aminophenyl)-1-methylethyl]benzene,bis[4-(3-aminophenoxy)phenyl]sulfone,bis[4-(4-aminophenoxy)phenyl]sulfone,2,2-bis[3-(3-aminophenoxy)phenyl]propane,2,2-bis[3-(4-aminophenoxy)phenyl]propane,2,2-bis[4-(3-aminophenoxy)phenyl]propane,2,2-bis[4-(4-aminophenoxy)phenyl]propane,2,2-bis[3-(3-aminophenoxy)phenyl]hexafluoropropane,2,2-bis[3-(4-aminophenoxy)phenyl]hexafluoropropane,2,2-bis[4-(3-aminophenoxy)phenyl]hexafluoropropane,2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane,4,4′-diamino-3,3′,5,5′-tetramethyldiphenylmethane,4,4′-diamino-3,3′,5,5′-tetraethyldiphenylmethane,4,4′-diamino-3,3′,5,5′-tetrapropyldiphenylmethane,4,4′-diamino-3,3′,5,5′-tetraisopropyldiphenylmethane,4,4′-diamino-3,3′,5,5′-tetrabutyldiphenylmethane,4,4′-diamino-3,3′-diethyl-5,5′-dimethyldiphenylmethane,4,4′-diamino-3,3′-dimethyldiphenylmethane,4,4′-diamino-3,3′-diethyldiphenylmethane,4,4′-diamino-3,3′,5,5′-tetramethoxydiphenylmethane,4,4′-diamino-3,3′,5,5′-tetraethoxydiphenylmethane,4,4′-diamino-3,3′,5,5′-tetrapropoxydiphenylmethane,4,4′-diamino-3,3′,5,5′-tetrabutoxydiphenylmethane, and4,47-diamino-3,3′-dimethoxydiphenylmethane.

The siloxane-modified polyimide used in the present invention can beprepared by the following method.

When tetracarboxylic acid dianhydride and diamine (including thesiloxane compound) are used as raw materials, the siloxane-modifiedpolyimide can be produced by any one of a method in which the abovematerials are heated up to 100° C. or higher, preferably 180° C. orhigher, in an organic solvent optionally in the presence of a catalyst(in an amount of 20 parts by weight or less based on the reactants) suchas tributylamine, triethylamine or triphenyl phosphite to directlyobtain a polyimide, a method in which tetracarboxylic acid and a diamineare allowed to react in an organic solvent at a temperature of 100° C.or lower to obtain a polyamic acid as a polyimide precursor, adehydrating catalyst (in an amount of 1 to 5 mol per mole of thetetracarboxylic acid dianhydride) such as p-toluenesulfonic acid isadded as required and the mixture is heated to form a polyimide, and amethod in which a dehydrating and ring-closing agent (in an amount of 2to 10 mol per mole of the tetracarboxylic acid dianhydride) selectedfrom acid anhydrides such as acetic acid anhydride, propionic acidanhydride and benzoic acid anhydride or carbodiimide compounds such asdicyclohexylcarbodiimide and optionally a ring-closing catalyst (in anamount of 2 to 10 mol per mole of the tetracarboxlyic acid dianhydride)such as pyridine, isoquinoline, imidazole or triethylamine are added tothe above polyamic acid and the polyamic acid is ring-closed at arelatively low temperature (approximately between room temperature and100° C.).

The organic solvents used for the above reactions include aprotic polarsolvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide,N,N-dimethylformamide, dimethylsulfoxide, sulfolane,hexamethylphosphoric acid triamide and 1,3-dimethyl-2-imidazolidone, andphenol-containing solvents such as phenol, cresol, xylenol andp-chlorophenol. Further, as required, the above organic solvent may beused as a mixture with benzene, toluene, xylene, methyl ethyl ketone,acetone, tetrahydrofuran, dioxane, monoglyme, diglyme, methylcellosolve, cellosolve acetate, methanol, ethanol, isopropanol,methylene chloride, chloroform, trichlene or nitrobenzene.

When tetracarboxylic acid dianhydride and diisocynate are used as rawmaterials, the siloxane-modified polyimide can be obtained according tothe above method where a polyimdie is directly obtained. In this case,the reaction temperature is preferably room temperature or higher,particularly preferably 60° C. or higher. The tetracarboxylic acid andeither the diamine or the diisocynate are allowed to react in equimolaramounts, whereby a polyimide having a high polymerization degree can beobtained. As required, an excess of one material may be used to producea polyimide so long as the amount of the material does not exceed by 10mol %.

The compound containing at least 2 methylallyl groups or the compoundcontaining 3 allyl or methylallyl groups as component (B), representedby the formula (1) or (IA), improves the heat resistance and thedielectric constant property of the cured resin composition. The itabove compounds are commercially easily available. Further, they can bealso synthesized by a conventional method.

The compound containing at least 2 maleimide groups as a component (c)is not specially limited, while compounds of the following formulae(4-1) to (4-5) are particularly preferred in view of electricreliability and solubility in a solvent. These compounds are generallycommercially available. Further, they can be also synthesized by aconventional method.

wherein p is an integer of 0 to 8.

In the amount ratio of the above components in the thermosettinglow-dielectric resin composition, the total content of the components(b) and (c) per 100 parts by weight of the component (a) is 10 to 900parts by weight, preferably 50 to 900 parts by weight, more preferably100 to 900 parts by weight. When the total content of the components (b)and (c) is smaller than the above lower limit, the resin compositionafter cured shows a decrease in heat resistance, particularly, a greatdecrease in Tg and Young's modulus, so that the resin composition is notsuitable for the intended use.

Further, the amount ratio of the components (b) and (c) is preferablyset such that the amount of allyl groups or methylallyl groups of thecomponent (B) per mole equivalent of maleimide groups of the component(c) is 0.1 to 2.0 mol equivalents. The amount of allyl groups ormethylallyl groups of the component (B) per mole equivalent of maleimidegroups of the component (c) is more preferably 0.3 to 1.8 molequivalents, still more preferably 0.5 to 1.5 mol equivalents. When theequivalent weight of the allyl group or the methylally groups is smallerthan the above lower limit, the cured resin composition shows poorelectric reliability. When the above equivalent weight is greater thanthe above upper limit, gelation takes place when the components weremixed, and an adhesive can be no longer prepared.

The components (a), (b) and (c) can be mixed in a solvent in which thecomponents are soluble. The solvent includes N-methyl-2-pyrrolidone,N,N-dimethylacetamide, N,N-dimethylformamide, dimethylsulfoxide,sulfolane, hexamethylphosphoric acid triamide,1,3-dimethyl-2-imidazolidone, hexane, benzene, toluene, xylene, methylethyl ketone, acetone, diethyl ether, tetrahydrofuran, dioxane,1,2-dimethoxymethane, diethylene glycol dimethyl ether, methylcellosolve, cellosolve acetate, methanol, ethanol, propanol,isopropanol, methyl acetate, ethyl acetate, acetonitrile, methylenechloride, chloroform, carbon tetrachloride, chlorobenzene,dichlorobenzene, dichloroethane and trichloroethane. These solvents areused as required in kinds and amounts suitable for dissolving eachcomponents.

The thermosetting low-dielectric resin composition may contain areaction promoter as required for promoting a reaction during drying orcuring under heat. The reaction promoter includes diazabicylcooctane,organic peroxides such as methyl ethyl ketone peroxide, cyclohexaneperoxide, 3,3,5-trimethylcyclohexanone peroxide, methylcyclohexanoneperoxide, methyl acetoacetate peroxide, acetyl acetone peroxide,1,1-bis(t-butylperoxy)-3,3,5-trimethylhexane,1,1-bis(t-butylperoxy)-cyclohexane, 2,2-bis(t-butylperoxy)octane,n-butyl-4,4-bis(t-butylperoxy)valerate, 2,2-bis(t-butylperoxy)butane,t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzenehydroperoxide, p-menthane hydroperoxide,2,5-dimethylhexane-2,5-dihydroperoxide, 1,1,3,3-tetramethylbutylhydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumylperoxide, α,α′-bis(t-butylperoxy-m-isopropyl)benzene,2,5-dimethyl-2,5-di(t-butylperoxy)hexane,2,5-dimethyl-2,5-di(t-butylperoxy)hexyne, acetyl peroxide, isobutylperoxide, octanoyl peroxide, decanoyl peroxide, benzoyl peroxide,lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, succinic acidperoxide, 2,4-dichlorobenzoyl peroxide, m-toluoyl peroxide,diisopropylperoxydicarbonate, di-2-ethylhexylperoxydicarbonate,di-n-propylperoxydicarbonate, bis(4-t-butylcyclohexyl)peroxydicarbonate,dimyristylperoxydicarbonate, di-2-ethoxyethylperoxydicarbonate,dimethoxyisopropylperoxydicarbonate,di(3-methyl-3-methoxybutyl)peroxydicarbonate, diallylperoxydicarbonate,t-butylperoxyacetate, t-butylperoxyisobutyrate, t-butylperoxypivalate,t-butylperoxyneodecanoate, cumylperoxyneodecanoate,t-butylperoxy-2-ethylhexanoate, t-butylperoxy-3,5,5-trimethylhexanoate,t-butylperoxylaurate, t-butylperoxybenzoate,di-t-butylperoxyisophthalate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane,t-butylperoxymaleate, t-butylperoxyisopropylcarbonate,cumylperoxyoctate, t-hexylperoxyneodecanoate, t-hexylperoxypivalate,t-butylperoxyneohexanoate, acetylcyclohexylsulfonyl peroxide andt-butylperoxyallylcarbonate, imidazoles such as 1,2-dimethylimidazole,1-methyl-2-ethylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole,2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole,1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole,1-benzyl-2-phenylimidazole-trimellitate, 1-benzyl-2-ethylimidazole,1-benzyl-2-ethyl-5-methylimidazole, 2-ethylimidazole,2-isopropylimidazole, 2-phenyl-4-benzylimidazole,1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole,1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-isopropylimidazole,1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazoliumtrimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4,-diamino-6-[2′-methylimidazolyl(1′)]-ethyl-s-triazine,2,4-diamino-6-[2′-ethyl-4-methylimidazolyl-(1′)]-ethyl-s-triazine,2,4-diamino-6-[2′-undecylimidazolyl-(1′)]-ethyl-s-triazine,2-methylimidazolium isocyanuric acid adduct, 2-phenylimidazoliumisocyanuric acid adduct,2,4-diamino-6-[2′-methylimidazolyl-(1′)]-ethyl-s-triazine-isocyanuricacid adduct, 2-phenyl-4,5-dihydroxymethylimidazole,2-phenyl-4-benzyl-5-hydroxymethylimidazole,4,4′-methylene-bis-(2-ethyl-5-methylimidazole),1-aminoethyl-2-methylimidazole,1-cyanoethyl-2-phenyl-4,5-di(cyanoethoxymethyl)imidazole,1-dodecyl-2-methyl-3-benzylimidazolium chloride,2-methylimidazole-benzotriazole adduct, 1-aminoethyl-2-ethylimidazole,1-(cyanoethylaminoethyl)-2-methylimidazole,N,N′-[2-methylimidazolyl-(1)-ethyl]-adipoyldiamide,N,N′-bis-(2-methylimidazolyl-1-ethyl)urea,N-(2-methylimidazolyl-1-ethyl)urea,N,N′-[2-methylimidazolyl-(1)-ethyl]dodecanedioyldiamide,N,N′-[2-methylimidazolyl-(1)-ethyl]eicosanedioyldiamide and1-benzyl-2-phenylimidazole-hydrochloride, and triphenyl phosphine.

Further, the thermosetting low-dielectric resin composition may containa filler having an average particle diameter of 1 μm or less forstabilizing the fluidity of the resin composition when the resincomposition is applied to a laminated board or a metal-clad laminate.The content of the filler based on the total solid content is 5 to 70%by weight, preferably 10 to 60% by weight, more preferably 20 to 50% byweight. When the above content is smaller than the above lower limit,the effect on fluidity stabilization is small. When it exceeds the aboveupper limit, the laminated board shows a decreased adhesion strength andhas an increased dielectric constant. The filler is selected, forexample, from silica, powdered quartz, alumina, calcium carbonate,magnesium oxide, a diamond powder, mica, a fluorine resin, a zirconpowder.

The laminated board and the metal-clad laminate to which the abovethermosetting low-dielectric resin composition is applied, provided bythe present invention, will be explained below.

A laminated board of one or more prepreg sheets in a semi-cured state,the prepreg being formed of a reinforcing fiber material impregnatedwith the above resin composition, can be prepared by applying a varnishprepared by dissolving the thermosetting low-dielectric resincomposition in the above organic solvent to the reinforcing fibermaterial such as a woven fabric or non-woven fabric, or impregnating thereinforcing fiber material with the composition, drying the compositionand laminating the prepreg sheet(s). In this case, the amount of theresin composition after drying is preferably such an amount that voidsof a fabric (cloth) can be fully filled. The thickness of the fabric is0.05 to 1 mm, preferably 0.1 to 0.5 mm, more preferably 0.1 to 0.2 mm.When the above thickness is too small, the fabric has no sufficientstrength. When it is too large, it is difficult to apply the resincomposition varnish to the fabric or impregnate the fabric with theresin composition varnish.

The material for the reinforcing fiber material is preferably aheat-resistant fiber. Specifically, the above material includes a carbonfiber, a glass fiber, an aramid fiber, an aromatic polyester fiber, aboron fiber, a silica fiber and a tetrafluorocarbon fiber. These fibersmay be long fibers, or they may be short fibers. A woven fabric or anon-woven fabric may be used. These reinforcing materials may be usedalone or in combination. It is particularly preferred to use an aramidfiber, an aromatic polyester fiber or a tetrafluorocarbon fiber.

The laminated board formed of prepreg sheet(s) prepared by applying theresin composition varnish to a fabric or impregnating a fabric with theresin composition varnish may be surface-smoothened with a hot laminatoror a calender.

According to the present invention, there is provided a metal-cladlaminate comprising the above laminated board, which is a laminateformed of a reinforcing fiber material and at least one prepreg sheetfilled with the above thermosetting low-dielectric resin composition andis in a semi-cured state, and a metal foil or foils which is or arestacked on and integrated with one surface or both surfaces of thelaminated board. The resin of the metal-clad laminate obtained by theabove laminating and integration is in a semi-cured state or a curedstate. The metal-clad laminate can be formed by attaching a metal foilor foils on one surface or both surfaces of the laminated board in asemi-cured state and integrating them with a press machine, a vacuumpress machine or a hot laminator. The metal foil is generally selectedfrom 5 μm to 200 μm thick foils of copper, cupro-nickel, silver, iron,42 alloy and stainless steel.

A protective film may be formed on a resin surface of the laminatedboard or one-side metal-clad laminate. The protective film includes apolypropylene film, a fluorine resin-based film, a polyethylene film, apolyethylene terephthalate film and paper. These films may be providedwith peeling properties with a silicone resin as required.

The above peeling-off protective film preferably has a 90° peel strengthof 0.01 to 7.0 g/cm. When the above peel strength is smaller than theabove lower limit, there is a problem that the peeling-off protectivefilm is easily peeled off during the transportation of the laminatedboard or the one-side metal-clad laminate. When the above peel strengthis greater than the above upper limit, the peeling-off protective filmis not cleanly peeled off and causes poor workability.

Having excellent flexibility, the thermosetting low-dielectric resincomposition of the present invention can be used as a film-like adhesiveor a sheet-like adhesive.

According to the present invention, further, there is provided a circuitlaminate material formed on a peel-off film or a metal foil and theabove thermosetting low-dielectric resin composition laminated on onesurface thereof as an adhesive.

The adhesive film and the resin-applied metal sheet of the presentinvention can be produced by applying the above resin composition to oneor both surfaces of a metal foil or to one surface of a peeling-off filmand drying the resin composition. In this case, the thickness of acoating formed of the resin composition is 5 to 100 μm, preferably 10 to70 μm. The metal foil is selected from foils which have a thickness of10 to 200 μm, preferably 100 μm or lass, particularly preferably 36 μmor less and are formed of copper, cupro-nickel, silver, iron, 42 alloyand stainless steel. When the above thickness is too large, it isdifficult to form a fine circuit, so that the thickness in the aboverange is preferred.

The peeling-off film for use in the adhesive film of the presentinvention is selected from peeling-off films having a thickness of 1 to200 μm, preferably 10 to 100 μm, and it works as a temporary support.The peeling-off film includes a polypropylene film, a fluorineresin-based film, a polyethylene film, a polyethylene terephthalate filmand paper. These films may be provided with peeling properties with asilicone resin as required.

The above peeling-off film preferably has a 90° peel strength of 0.01 to7.0 g/cm for the same reason as that described concerning the abovepeeling-off film. In the resin-applied metal foil having an adhesivelayer formed by application of the above resin composition on one orboth surfaces of a metal foil, a peeling-off protective film may beprovided on the adhesive layer. The protective film can be selected fromthe above peeling-off films.

As described above, the present invention provides a resin compositionwhich can be suitably used as a laminate material for a printed circuitboard, etc., since it has a low dielectric constant and excellent heatresistance and has a sufficient peel strength at room temperature, alaminated board to which the above resin composition is applied, and ametal-clad laminate to which the above laminated board is applied.

Further, the present invention provides a circuit laminate materialwhich has a low dielectric constant and excellent heat resistance andhas a sufficient peel strength at room temperature, and which is freefrom breaking and scattering of a resin in the vicinity of a cut portionduring cutting and therefore has excellent handling properties. Thecircuit laminate material of the present invention is suitable for usein a printed circuit board.

The present invention will be explained more in detail with reference toExamples hereinafter.

EXAMPLES Synthesis of Siloxane-modified Polyimide Synthesis Example 1

29.42 Grams (72 mmol) of 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 6.96g (28 mmol) of diaminosiloxane represented by the above formula (5) inwhich Y=NH₂, R=propyl and n=1, 35.83 g (100 mol) of3,3′,4,4′-diphenylsulfotetracarboxylic acid dianhydride and 300 ml ofN-methyl-2-pyrrolidone (to be referred to as “NMP” hereinafter) wereincorporated under a temperature of ice and stirred continuously for 1hour. Then, the resultant solution allowed to react at room temperaturefor 2 hours to synthesize a polyamic acid. To the obtained polyamic acidwere added 50 ml of toluene and 1.0 g of p-toluenesulfonic acid, and themixture was heated to 160° C. While water azeotropically boiling withtoluene was separated, an imidation was carried out for 3 hours. Then,toluene was distilled off, and the resultant siloxane-modified polyimidevarnish was poured into methanol to form a precipitate, followed by thesteps of separating, pulverizing, washing and drying the precipitate, togive 61.9 g (yield 94%) of siloxane-modified polyimide containingstructural units of the above formulae (2a) and (2b) in a (2a):(2b)molar ratio of 72:28 and having a molecular weight of 18,000, a Tg of30° C. and dielectric constant of 2.8.

The obtained siloxane-modified polyimide was measured for infraredabsorption spectrum to show typical imide absorptions at 1,718 cm⁻¹ and1,783 cm⁻¹.

Synthesis Example 2

30.39 Grams (74 mmol) of 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 19.94g (26 mmol) of diaminosiloxane represented by the above formula (5) inwhich Y=NH₂, R=propyl and n=8, 29.42 g (100 mol) of3,3′,4,4′-biphenyltetracarboxylic acid dianhydride and 300 ml of NMPwere used, and procedures in Synthesis Example 1 were repeated, to give72.3 g (yield 95%) of siloxane-modified polyimide containing structuralunits of the formulae (2a) and (2b) in a (2a):(2b) molar ratio of 74:26and having a molecular weight of 19,000, a Tg of 45° C. and dielectricconstant of 2.9.

The obtained siloxane-modified polyimide was measured for infraredabsorption spectrum to show typical imide absorptions at 1,718 cm⁻¹ and1,783 cm⁻¹.

Synthesis Example 3

41.48 Grams (80 mmol) of 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 15.54(20 mmol) of diaminosiloxane represented by the above formula (5) inwhich Y=NH₂, R=propyl and n=8, 29.42 g (100 mol) of2,3′,3,4′-biphenyltetracarboxylic acid dianhydride and 300 ml of NMPwere used, and procedures in Synthesis Example 1 were repeated, to give81.2 g (yield 94%) of siloxane-modified polyimide containing structuralunits of the formulae (2a) and (2b) in a (2a):(2b) molar ratio of 80:20and having a molecular weight of 10,000, a Tg of 60° C. and dielectricconstant of 2.9.

The obtained siloxane-modified polyimide was measured for infraredabsorption spectrum to show typical imide absorptions at 1,718 cm⁻¹ and1,783 cm⁻¹.

Preparation of Thermosetting Low-dielectric Resin Composition ResinComposition Preparation Example 1

100 Parts by weight of the siloxane-modified polyimide obtained inSynthesis Example 3, 272 parts by weight of the compound of the formula(4-2) and 128 parts by weight of the compound of the formula (1)(methylallyl groups had a mole equivalent of 0.5 per mole equivalent ofmaleimide groups) were added to tetrahydrofuran, and fully mixed anddissolved, to give a resin composition varnish having a solid content of30% by weight.

Resin Composition Preparation Example 2

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 1 except that the amount of the compoundof the formula (4-2) was changed to 206 parts by weight and that theamount of the compound of the formula (1) was changed to 193 parts byweight (methylallyl groups had a mole equivalent of 1.0 per moleequivalent of maleimide groups).

Resin Composition Preparation Example 3

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 1 except that the amount of the compoundof the formula (4-2) was changed to 166 parts by weight and that theamount of the compound of the formula (1) was changed to 234 parts byweight (methylallyl groups had a mole equivalent of 1.5 per moleequivalent of maleimide groups).

Resin Composition Preparation Example 4

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 1 except that the amount of the compoundof the formula (4-2) was changed to 52 parts by weight and that theamount of the compound of the formula (1) was changed to 49 parts byweight (methylallyl groups had a mole equivalent of 1.0 per moleequivalent of maleimide groups).

Resin Composition Preparation Example 5

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 1 except that the amount of the compoundof the formula (4-2) was changed to 464 parts by weight and that theamount of the compound of the formula (1) was changed to 435 parts byweight (methylallyl groups had a mole equivalent of 1.0 per moleequivalent of maleimide groups).

Resin Composition Preparation Example 6

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 1 except that 272 parts by weight of thecompound of the formula (4-2) was replaced with 251 parts by weight ofthe compound of the formula (4-1) and that the amount of the compound ofthe formula (1) was changed from 128 parts by weight to 148 parts byweight (methylallyl groups had a mole equivalent of 1.0 per moleequivalent of maleimide groups).

Resin Composition Preparation Example 7

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 1 except that 272 parts by weight of thecompound of the formula (4-2) was replaced with 228 parts by weight ofthe compound of the formula (4-3) and that the amount of the compound ofthe formula (1) was changed from 128 parts by weight to 173 parts byweight (methylallyl groups had a mole equivalent of 1.0 per moleequivalent of maleimide groups).

Resin Composition Preparation Example 8

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 1 except that 272 parts by weight of thecompound of the formula (4-2) was replaced with 218 parts by weight of acompound of the formula (4-4) in which p was zero (0) and that theamount of the compound of the formula (1) was changed from 128 parts byweight to 180 parts by weight (methylallyl groups had a mole equivalentof 1.0 per mole equivalent of maleimide groups).

Resin Composition Preparation Example 9

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 1 except that 272 parts by weight of thecompound of the formula (4-2) was replaced with 266 parts by weight of acompound of the formula (4-4) in which p was 4 and that the amount ofthe compound of the formula (1) was changed from 128 parts by weight to134 parts by weight (methylallyl groups had a mole equivalent of 1.0 permole equivalent of maleimide groups).

Resin Composition Preparation Example 10

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 1 except that 272 parts by weight of thecompound of the formula (4-2) was replaced with 298 parts by weight of acompound of the formula (4-4) in which p was 8 and that the amount ofthe compound of the formula (1) was changed from 128 parts by weight to104 parts by weight (methylallyl groups had a mole equivalent of 1.0 permole equivalent of maleimide groups).

Resin Composition Preparation Example 11

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 1 except that 272 parts by weight of thecompound of the formula (4-2) was replaced with 247 parts by weight ofthe compound of the formula (4-5) and that the amount of the compound ofthe formula (1) was changed from 128 parts by weight to 155 parts byweight (methylallyl groups had a mole equivalent of 1.0 per moleequivalent of maleimide groups).

Resin Composition Preparation Example 12

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 2 except that the siloxane-modifiedpolyimide obtained in Synthesis Example 3 was replaced with thesiloxane-modified polyimide obtained in Synthesis Example 1.

Resin Composition Preparation Example 13

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 2 except that the siloxane-modifiedpolyimide obtained in Synthesis Example 3 was replaced with thesiloxane-modified polyimide obtained in Synthesis Example 2.

Resin Composition Preparation Example 14

A resin composition varnish was obtained by dispersing 150 parts byweight of a silica filler in the same resin composition varnish as thatobtained in Resin Composition Preparation Example 2.

Resin Composition Preparation Example 15

A resin composition varnish was obtained by dispersing 300 parts byweight of a silica filler in the same resin composition varnish as thatobtained in Resin Composition Preparation Example 2.

Resin Composition Preparation Example 16

100 Parts by weight of the siloxane-modified polyimide resin obtained inSynthesis Example 3, 314 parts by weight of the compound of the formula(4-2) and 86 parts by weight of the compound of the formula (1A) inwhich R was methyl (methylallyl groups had a mole equivalent of 0.5 permole equivalent of maleimide groups) were added to tetrahydrofuran andthese components were fully mixed and dissolved, to give a resincomposition varnish having a solid content of 30% by weight.

Resin Composition Preparation Example 17

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 16 except that the amount of thecompound of the formula (4-2) was changed to 259 parts by weight andthat the amount of the compound of the formula (1A) in which R wasmethyl was changed to 141 parts by weight (methylallyl groups had a moleequivalent of 1.0 per mole equivalent of maleimide groups).

Resin Composition Preparation Example 18

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 16 except that the amount of thecompound of the formula (4-2) was changed to 221 parts by weight andthat the amount of the compound of the formula (1A) in which R wasmethyl was changed to 179 parts by weight (methylallyl groups had a moleequivalent of 1.5 per mole equivalent of maleimide groups).

Resin Composition Preparation Example 19

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 16 except that the amount of thecompound of the formula (4-2) was changed to 64 parts by weight and thatthe amount of the compound of the formula (1A) in which R was methyl waschanged to 36 parts by weight (methylallyl groups had a mole equivalentof 1.0 per mole equivalent of maleimide groups).

Resin Composition Preparation Example 20

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 16 except that the amount of thecompound of the formula (4-2) was changed to 584 parts by weight andthat the amount of the compound of the formula (1A) in which R wasmethyl was changed to 316 parts by weight (methylallyl groups had a moleequivalent of 1.0 per mole equivalent of maleimide groups).

Resin Composition Preparation Example 21

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 16 except that 314 parts by weight ofthe compound of the formula (4-2) was replaced with 298 parts by weightof the compound of the formula (4-1) and that the amount of the compoundof the formula (1A) in which R was methyl was changed from 86 parts byweight to 102 parts by weight (methylallyl groups had a mole equivalentof 1.0 per mole equivalent of maleimide groups).

Resin Composition Preparation Example 22

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 16 except that 314 parts by weight ofthe compound of the formula (4-2) was replaced with 278 parts by weightof the compound of the formula (4-3) and that the amount of the compoundof the formula (1A) in which R was methyl was changed from 86 parts byweight to 122 parts by weight (methylallyl groups had a mole equivalentof 1.0 per mole equivalent of maleimide groups).

Resin Composition Preparation Example 23

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 16 except that 314 parts by weight ofthe compound of the formula (4-2) was replaced with 271 parts by weightof the compound of the formula (4-4) in which p was zero (0) and thatthe amount of the compound of the formula (1A) in which R was methyl waschanged from 86 parts by weight to 129 parts by weight (methylallylgroups had a mole equivalent of 1.0 per mole equivalent of maleimidegroups).

Resin Composition Preparation Example 24

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 16 except that 314 parts by weight ofthe compound of the formula (4-2) was replaced with 309 parts by weightof the compound of the formula (4-4) in which p was 4 and that theamount of the compound of the formula (1A) in which R was methyl waschanged from 86 parts by weight to 90 parts by weight (methylallylgroups had a mole equivalent of 1.0 per mole equivalent of maleimidegroups).

Resin Composition Preparation Example 25

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 16 except that 314 parts by weight ofthe compound of the formula (4-2) was replaced with 333 parts by weightof the compound of the formula (4-4) in which p was 8 and that theamount of the compound of the formula (1A) in which R was methyl waschanged from 86 parts by weight to 67 parts by weight (methylallylgroups had a mole equivalent of 1.0 per mole equivalent of maleimidegroups).

Resin Composition Preparation Example 26

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 16 except that 314 parts by weight ofthe compound of the formula (4-2) was replaced with 294 parts by weightof the compound of the formula (4-5) and that the amount of the compoundof the formula (1A) in which R was methyl was changed from 86 parts byweight to 106 parts by weight (methylallyl groups had a mole equivalentof 1.0 per mole equivalent of maleimide groups).

Resin Composition Preparation Example 27

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 17 except that the siloxane-modifiedpolyimide obtained in Synthesis Example 3 was replaced with the samesiloxane-modified polyimide as that obtained in Synthesis Example 1.

Resin Composition Preparation Example 28

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 17 except that the siloxane-modifiedpolyimide obtained in Synthesis Example 3 was replaced with the samesiloxane-modified polyimide as that obtained in Synthesis Example 2.

Resin Composition Preparation Example 29

A resin composition varnish was obtained by dispersing 150 parts byweight of a silica filler in the same resin composition varnish as thatobtained in Resin Composition Preparation Example 17.

Resin Composition Preparation Example 30

A resin composition varnish was obtained by dispersing 300 parts byweight of a silica filler in the same resin composition varnish as thatobtained in Resin Composition Preparation Example 17.

Resin Composition Preparation Example 31

100 Parts by weight of the siloxane-modified polyimide resin obtained inSynthesis Example 3, 325 parts by weight of the compound of the formula(4-2) and 75 parts by weight of the compound of the formula (1A) inwhich R was hydrogen (allyl groups had a mole equivalent of 0.5 per moleequivalent of maleimide groups) were added to tetrahydrofuran and thesecomponents were fully mixed and dissolved, to give a resin compositionvarnish having a solid content of 30% by weight.

Resin Composition Preparation Example 32

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 31 except that the amount of thecompound of the formula (4-2) was changed to 273 parts by weight andthat the amount of the compound of the formula (1A) in which R washydrogen was changed to 127 parts by weight (allyl groups had a moleequivalent of 1.0 per mole equivalent of maleimide groups).

Resin Composition Preparation Example 33

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 31 except that the amount of thecompound of the formula (4-2) was changed to 236 parts by weight andthat the amount of the compound of the formula (1A) in which R washydrogen was changed to 164 parts by weight (allyl groups had a moleequivalent of 1.5 per mole equivalent of maleimide groups).

Resin Composition Preparation Example 34

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 31 except that the amount of thecompound of the formula (4-2) was changed to 68 parts by weight and thatthe amount of the compound of the formula (1A) in which R was hydrogenwas changed to 32 parts by weight (allyl groups had a mole equivalent of1.0 per mole equivalent of maleimide groups).

Resin Composition Preparation Example 35

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 31 except that the amount of thecompound of the formula (4-2) was changed to 615 parts by weight andthat the amount of the compound of the formula (1A) in which R washydrogen was changed to 285 parts by weight (allyl groups had a moleequivalent of 1.0 per mole equivalent of maleimide groups).

Resin Composition Preparation Example 36

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 31 except that 325 parts by weight ofthe compound of the formula (4-2) was replaced with 310 parts by weightof the compound of the formula (4-1) and that the amount of the compoundof the formula (1A) in which R was hydrogen was changed from 75 parts byweight to 90 parts by weight (allyl groups had a mole equivalent of 1.0per mole equivalent of maleimide groups).

Resin Composition Preparation Example 37

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 31 except that 325 parts by weight ofthe compound of the formula (4-2) was replaced with 291 parts by weightof the compound of the formula (4-3) and that the amount of the compoundof the formula (1A) in which R was hydrogen was changed from 75 parts byweight to 109 parts by weight (allyl groups had a mole equivalent of 1.0per mole equivalent of maleimide groups).

Resin Composition Preparation Example 38

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 31 except that 325 parts by weight ofthe compound of the formula (4-2) was replaced with 284 parts by weightof the compound of the formula (4-4) in which p was 0 (zero) and thatthe amount of the compound of the formula (1) in which R was hydrogenwas changed from 75 parts by weight to 105 parts by weight (allyl groupshad a mole equivalent of 1.0 per mole equivalent of maleimide groups).

Resin Composition Preparation Example 39

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 31 except that 325 parts by weight ofthe compound of the formula (4-2) was replaced with 320 parts by weightof the compound of the formula (4-4) in which p was 4 and that theamount of the compound of the formula (1) in which R was hydrogen waschanged from 75 parts by weight to 80 parts by weight (allyl groups hada mole equivalent of 1.0 per mole equivalent of maleimide groups).

Resin Composition Preparation Example 40

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 31 except that 325 parts by weight ofthe compound of the formula (4-2) was replaced with 341 parts by weightof the compound of the formula (4-4) in which p was 8 and that theamount of the compound of the formula (1A) in which R was hydrogen waschanged from 75 parts by weight to 59 parts by weight (allyl groups hada mole equivalent of 1.0 per mole equivalent of maleimide groups).

Resin Composition Preparation Example 41

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 31 except that 325 parts by weight ofthe compound of the formula (4-2) was replaced with 305 parts by weightof the compound of the formula (4-5) and that the amount of the compoundof the formula (1A) in which R was hydrogen was changed from 75 parts byweight to 94 parts by weight (allyl groups had a mole equivalent of 1.0per mole equivalent of maleimide groups).

Resin Composition Preparation Example 42

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 32 except that the siloxane-modifiedpolyimide obtained in Synthesis Example 3 was replaced with the samesiloxane-modified polyimide as that obtained in Synthesis Example 1.

Resin Composition Preparation Example 43

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 32 except that the siloxane-modifiedpolyimide obtained in Synthesis Example 3 was replaced with the samesiloxane-modified polyimide as that obtained in Synthesis Example 2.

Resin Composition Preparation Example 44

A resin composition varnish was obtained by dispersing 150 parts byweight of a silica filler in the same resin composition varnish as thatobtained in Resin Composition Preparation Example 32.

Resin Composition Preparation Example 45

A resin composition varnish was obtained by dispersing 300 parts byweight of a silica filler in the same resin composition varnish as thatobtained in Resin Composition Preparation Example 32.

EXAMPLES Examples 1-15

100 Parts by weight of an aromatic polyester non-woven fabric (thickness0.1 mm, supplied by Kuraray Ltd.) was impregnated with 120 parts byweight, as a solid content, of each of the resin composition varnishesobtained in Resin Composition Preparation Examples 1 to 15, eachimpregnated non-woven fabric was dried in a hot air circulating dryer at140° C. for 5 minutes to obtain prepregs. The prepregs were tack-freeand flexible so that they were excellent in workability. Four sheets ofeach prepreg were independently stacked one on another, and 18 μm thickcopper foils were placed on the outermost surfaces of each laminate, onecopper foil on one surface and the other copper foil on the othersurface. The resultant sets were shaped under a pressure of 20 kg/cm²under heating conditions of 200° C. and 2 hours, to give double-sidecopper-clad laminates having a thickness of 0.4 mm each. The laminateswere measured or tested as will be described later. Table 1 shows theresults.

Example 16

A double-side copper clad laminate having a thickness of 0.4 mm wasobtained in the same manner as in Examples 1 to 15 except that the resincomposition varnish obtained in Resin Composition Preparation Example 2was used and that the aromatic polyester non-woven fabric was replacedwith an aramid non-woven fabric (thickness 0.1 mm, supplied by E. I. duPont de Nemours & Co.). The laminate was measured or tested as will bedescribed later. Table 1 shows the results.

Example 17

A double-side copper clad laminate having a thickness of 0.4 mm wasobtained in the same manner as in Examples 1 to 15 except that the resincomposition varnish obtained in Resin Composition Preparation Example 2was used and that the aromatic polyester non-woven fabric was replacedwith a tetrafluorocarbon non-woven fabric (thickness 0.1 mm, supplied byTomoegawa). The laminate was measured or tested as will be describedlater. Table 1 shows the results.

Example 18

A double-side copper clad laminate having a thickness of 0.4 mm wasobtained in the same manner as in Examples 1 to 15 except that the resincomposition varnish obtained in Resin Composition Preparation Example 2was used and that the 18 μm thick copper foils were replaced with 18 μmthick 42 alloy foils. The laminate was measured or tested as will bedescribed later. Table 1 shows the results.

Comparative Example 1

100 Parts by weight of the same siloxane-modified polyimide resin asthat obtained in Synthesis Example 3 and 400 parts by weight of thecompound of the formula (4-2) were added to tetrahydrofuan and fullymixed and dissolved to obtain a resin composition having a solid contentof 30% by weight. Then, the resin composition was used to prepare adouble-side copper-clad laminate having a thickness of 0.4 mm in thesame manner as in Examples 1 to 15. The laminate was measured or testedas will be described later. Table 1 shows the results.

Comparative Example 2

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 1 except that the siloxane-modifiedpolyimide obtained in Synthesis Example 3 was replaced with anacrylonitrile-butadiene copolymer. Then, the resin composition varnishwas used to prepare a double-side copper-clad laminate having athickness of 0.4 mm in the same manner as in Examples 1 to 15. Thelaminate was measured or tested as will be described later. Table 1shows the results.

TABLE 1 Properties Heat resistance Dielectric Peel against constantstrength soldering PCBT Ex. 1 3.0 1.2 kg/cm No problem No short circuitEx. 2 2.9 1.2 kg/cm No problem No short circuit Ex. 3 3.0 1.3 kg/cm Noproblem No short circuit Ex. 4 3.0 1.3 kg/cm No problem No short circuitEx. 5 3.0 1.2 kg/cm No problem No short circuit Ex. 6 3.0 1.4 kg/cm Noproblem No short circuit Ex. 7 2.9 1.3 kg/cm No problem No short circuitEx. 8 2.8 1.2 kg/cm No problem No short circuit Ex. 9 2.9 1.3 kg/cm Noproblem No short circuit Ex. 10 3.0 1.2 kg/cm No problem No shortcircuit Ex. 11 2.9 1.2 kg/cm No problem No short circuit Ex. 12 2.8 1.4kg/cm No problem No short circuit Ex. 13 2.9 1.4 kg/cm No problein Noshort circuit Ex. 14 3.0 1.3 kg/cm No problem No short circuit Ex. 153.0 1.2 kg/cm No problem No short circuit Ex. 16 2.9 1.3 kg/cm Noproblem No short circuit Ex. 17 2.9 1.4 kg/cm No problem No shortcircuit Ex. 18 3.0 1.2 kg/cm No problem No short circuit CEx. 1 3.3 1.4kg/cm Copper foil No short circuit swollen CEx. 2 3.5 1.2 kg/cm Noproblem No short circuit Ex. = Example, CEx. = Comparative Example

(Evaluation methods)

Dielectric constant: A capacitance was measured at a frequency of 1 MHzaccording to JIS C6481 (specific dielectric constant and dielectrictangent), to determine a dielectric constant.

Peel strength: Measured according to JIS C6481 (peel strength).

Heat resistance against soldering: Measured according to JIS C6481 (heatresistance against soldering), and an appearance was studied for aproblem.

PCBT (Pressure Cooker Bias Test): A pattern having a line-line distanceof 100 μm was formed on the laminate surface by etching, a 0.1 mm thickprepreg sheet was laminated on the pattern, and the resultant set wasshaped under a pressure of 20 kg/cm² under heat at a temperature of 200°C. for 2 hours to obtain a test sample. The test sample was studied fora short circuit between lines under conditions of an applied voltage of5 V, 121° C., 2 atmospheric pressures, 100% RH and 1,000 hours.

Examples 19-48

100 Parts by weight of an aromatic polyester non-woven fabric (thickness0.1 mm, supplied by Kuraray Ltd.) was impregnated with 120 parts byweight, as a solid content, of each of the resin composition varnishesobtained in Resin Composition Preparation Examples 16 to 45, eachimpregnated non-woven fabric was dried in a hot air circulating dryer at140° C. for 5 minutes to obtain prepregs. The prepregs were tack-freeand flexible so that they were excellent in workability. Four sheets ofthe each prepreg were independently stacked one on another, and 18 μmthick copper foils were placed on the outermost surfaces of eachlaminate, one copper foil on one surface and the other copper foil onthe other surface. The resultant sets were respectively shaped under apressure of 20 kg/cm² under heating conditions of 200° C. and 2 hours,to give double-side copper-clad laminates having a thickness of 0.4 mmeach. The laminates were measured or tested in the same manner as inExamples 1 to 18. Table 2 shows the results.

Example 49

A double-side copper clad laminate having a thickness of 0.4 mm wasobtained in the same manner as in Examples 19 to 48 except that thearomatic polyester non-woven fabric was replaced with an aramidnon-woven fabric (thickness 0.1 mm, supplied by E. I. du Pont de Nemours& Co.). The laminate was measured or tested in the same manner as inExamples 1 to 18. Table 2 shows the results.

Example 50

A double-side copper clad laminate having a thickness of 0.4 mm wasobtained in the same manner as in Examples 19 to 48 except that thearomatic polyester non-woven fabric was replaced with atetrafluorocarbon non-woven fabric (thickness 0.1 mm, supplied byTomoegawa). The laminate was measured or tested in the same manner as inExamples 1 to 18. Table 2 shows the results.

Example 51

A double-side copper clad laminate having a thickness of 0.4 mm wasobtained in the same manner as in Examples 19 to 48 except that the 18μm thick copper foils were replaced with 18 μm thick 42 alloy foils. Thelaminate was measured or tested in the same manner as in Examples 1 to18. Table 2 shows the results.

Comparative Example 3

100 Parts by weight of the same siloxane-modified polyimide resin asthat obtained in Synthesis Example 3 and 400 parts by weight of thecompound of the formula (4-2) were added to tetrahydrofuan and fullymixed and dissolved to obtain a resin composition having a solid contentof 30% by weight. Then, the resin composition was used to prepare adouble-side copper-clad laminate having a thickness of 0.4 mm in thesame manner as in Examples 19 to 48. The laminate was measured or testedin the same manner as in Examples 1 to 18. Table 2 shows the results.

Comparative Example 4

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 16 except that the siloxane-modifiedpolyimide obtained in Synthesis Example 3 was replaced with anacrylonitrile-butadiene copolymer. Then, the resin composition varnishwas used to prepare a double-side copper-clad laminate having athickness of 0.4 mm in the same manner as in Examples 19 to 48. Thelaminate was measured or tested in the same manner as in Examples 1 to18. Table 2 shows the results.

TABLE 2 Properties Heat resistance Dielectric Peel against constantstrength soldering PCBT Ex. 19 3.0 1.2 kg/cm No problem No short circuitEx. 20 2.9 1.2 kg/cm No problem No short circuit Ex. 21 3.0 1.3 kg/cm Noproblem No short circuit Ex. 22 3.0 1.3 kg/cm No problem No shortcircuit Ex. 23 3.0 1.2 kg/cm No problem No short circuit Ex. 24 3.0 1.4kg/cm No problem No short circuit Ex. 25 2.9 1.3 kg/cm No problem Noshort circuit Ex. 26 2.8 1.2 kg/cm No problem No short circuit Ex. 272.9 1.3 kg/cm No problem No short circuit Ex. 28 3.0 1.2 kg/cm Noproblem No short circuit Ex. 29 2.9 1.2 kg/cm No problem No shortcircuit Ex. 30 2.8 1.4 kg/cm No problem No short circuit Ex. 31 2.9 1.4kg/cm No problem No short circuit Ex. 32 3.0 1.3 kg/cm No problem Noshort circuit Ex. 33 3.0 1.2 kg/cm No problem No short citcuit Ex. 342.9 1.3 kg/cm No problem No short circuit Ex. 35 2.9 1.4 kg/cm Noproblem No short circuit Ex. 36 3.0 1.2 kg/cm No problem No shortcircuit Ex. 37 2.9 1.2 kg/cm No problem No short circuit Ex. 38 2.8 1.3kg/cm No problem No short circuit Ex. 39 2.9 1.3 kg/cm No problem Noshort circuit Ex. 40 2.9 1.2 kg/cm No problem No short circuit Ex. 413.0 1.3 kg/cm No problem No short circuit Ex. 42 2.8 1.4 kg/cm Noproblem No short circuit Ex. 43 3.0 1.2 kg/cm No problem No shortcircuit Ex. 44 3.0 1.2 kg/cm No problem No short circuit Ex. 45 2.9 1.3kg/cm No problem No short circuit Ex. 46 3.0 1.2 kg/cm No problem Noshort circuit Ex. 47 2.9 1.2 kg/cm No problem No short circuit Ex. 483.0 1.4 kg/cm No problem No short circuit Ex. 49 2.8 1.2 kg/cm Noproblem No short circuit Ex. 50 2.8 1.2 kg/cm No problem No shortcircuit Ex. 51 3.0 1.3 kg/cm No problem No short circuit CEx. 3 3.3 1.4kg/cm Copper foil No short circuit swollen CEx. 4 3.5 1.1 kg/cm Noproblem No short circuit Ex. = Example

Examples 52-66

Each of the resin composition varnishes obtained in Resin CompositionPreparation Examples 1 to 15 was applied to one surface of a 18 μm thickcopper foil so as to form a dry adhesive layer having a thickness of 60μm, and the copper foils having the adhesive layer each were dried in ahot air circulating dryer at 140° C. for 5 minutes, to obtainresin-applied copper foils (a circuit laminating material).

Separately, both surfaces of each of the same 0.4 mm thick double-sidecopper-clad laminates as those obtained in Examples 1 to 15 were etchedin portions requiring no copper foil, to obtain inner-layer circuitboards. Then, the above resin-applied copper foils were stacked on thecorresponding inner-layer circuit boards such that the resin surface ofeach resin-applied copper foil was attached to the inner-layer circuitof each, and the resultant sets were shaped under a pressure of 20kg/cm² under heating conditions of 200° C. for 2 hours, to obtainmulti-layered copper-clad laminates. The laminates were measured ortested in the same manner as in Example 1. Further, the resin-appliedcopper foils in a semi-cured state were punched out with a die, and endsurfaces thereof were visually observed to determine “scattering”. Table3 shows the results.

Example 67

An inner-layer-possessing multi-layered copper-clad laminate wasobtained in the same manner as in Examples 52 to 66 except that thevarnish obtained in Resin Composition Preparation Example 2 was used andthat the 18 μm thick copper foil was replaced with a 18 μm thick 42alloy foil. Table 3 shows the results.

Example 68

The resin composition varnish obtained in Resin Composition PreparationExample 2 was applied to one surface of a 38 μm thick polyethyleneterephthalate film treated so as to be peeled off, such that a dryadhesive layer having a thickness of 60 μm was to be formed, and thefilm having the adhesive layer was dried in a hot air circulating dryerat 140° C. for 5 minutes, to obtain an adhesive film (a circuitlaminating material). When the adhesive film was cut with a knife, itwas free from cracking and scattering of a resin in the vicinity of cutportions, so that it was excellent in handling properties. Then, a 18 μmthick copper foil was attached to the adhesive surface of the adhesivefilm, to obtain a resin-applied copper foil. In this manner, a pluralityof resin-applied copper foils, which are included in the circuitlaminate material of the present invention, were prepared.

Separately, 100 parts by weight of an aromatic polyester non-wovenfabric (thickness 0.1 mm, supplied by Kuraray Ltd.) was impregnated with120 parts by weight, as a solid content, of the resin compositionvarnish obtained in Resin Composition Preparation Example 2, theimpregnated non-woven fabric was dried in a hot air circulating dryer at140° C. for 5 minutes to obtain prepreg. Four sheets of the prepreg werestacked one on another, and 18 μm thick copper foils were placed on theoutermost surfaces of the laminate, one copper foil on one surface andthe other copper foil on the other surface. The resultant set was shapedunder a pressure of 20 kg/cm² under heating conditions of 200° C., togive a double-side copper-clad laminate having a thickness of 0.4 mm.Further, surfaces of the double-side copper-clad laminate were etched inportions requiring no copper foil, to obtain an inner-layer circuitboard. Then, the above resin-applied copper foils were stacked on boththe surfaces of the inner-layer circuit board such that the resinsurface of each resin-applied copper foil was attached to eachinner-layer circuit. Then, the polyethylene terephthalate films treatedso as to be peeled off were peeled off, and then 18 μm thick copperfoils were stacked on the outermost surfaces, and the resultant set wasshaped under a pressure of 20 kg/cm² under heating conditions of 200° C.for 2 hours, to obtain a multi-layered copper-clad laminate. Thelaminate was measured or tested in the same manner as in Example 52.Table 3 shows the results.

Comparative Example 5

100 Parts by weight of the same siloxane-modified polyimide resin asthat obtained in Synthesis Example 3 and 400 parts by weight of thecompound of the formula (4-2) were added to tetrahydrofuan and fullymixed and dissolved to obtain a resin composition having a solid contentof 30% by weight. Then, the resin composition was used to prepare aninner-layer-circuit-possessing copper-clad laminate in the same manneras in Examples 52 to 66. The laminate was measured or tested in the samemanner as in Example 52. Table 3 shows the results.

Comparative Example 6

179 Parts by weight of the compound of the formula (4-2) and 168 partsby weight of the compound of the formula (1) (methylallyl groups had amole equivalent of 1.0 per mole equivalent of maleimide groups) wereadded to tetrahydrofuan and fully mixed and dissolved to obtain a resincomposition having a solid content of 30% by weight. Then, the resincomposition was used to prepare an inner-layer-circuit-possessingcopper-clad laminate in the same manner as in Examples 52 to 66. Thelaminate was measured or tested in the same manner as in Example 52.Table 3 shows the results.

Comparative Example 7

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 1 except that the siloxane-modifiedpolyimide obtained in Synthesis Example 3 was replaced with anacrylonitrile-butadiene copolymer. Then, the resin composition varnishwas used to prepare an inner-layer-circuit-possessing copper-cladlaminate in the same manner as in Examples 52 to 66. The laminate wasmeasured or tested in the same manner as in Example 52. Table 3 showsthe results.

TABLE 3 Properties Heat resistance Dielectric Peel against constantstrength soldering Scattering PCBT Ex. 52 3.0 1.2 kg/cm No problem Noburr No short circuit Ex. 53 2.9 1.2 kg/cm No problem No burr No shortcircuit Ex. 54 3.0 1.3 kg/cm No problem No burr No short circuit Ex. 553.0 1.3 kg/cm No problem No burr No short circuit Ex. 56 3.0 1.2 kg/cmNo problem No burr No short circuit Ex. 57 3.0 1.4 kg/cm No problem Noburr No short circuit Ex. 58 2.9 1.3 kg/cm No problem No burr No shortcircuit Ex. 59 2.8 1.2 kg/cm No problem No burr No short circuit Ex. 602.9 1.3 kg/cm No problem No burr No short circuit Ex. 61 3.0 1.2 kg/cmNo problem No burr No short circuit Ex. 62 2.9 1.2 kg/cm No problem Noburr No short circuit Ex. 63 2.8 1.4 kg/cm No problem No burr No shortcircuit Ex. 64 2.9 1.4 kg/cm No problem No burr No short circuit Ex. 653.0 1.3 kg/cm No problem No burr No short circuit Ex. 66 3.0 1.2 kg/cmNo problem No burr No short circuit Ex. 67 2.9 1.2 kg/cm No problem Noburr No short circuit Ex. 68 3.0 1.2 kg/cm No problem No burr No shortcircuit CEx. 5 3.3 1.4 kg/cm Copper foil No burr No short swollencircuit CEx. 6 2.8 1.3 kg/cm No problem Burr No short circuit CEx. 7 3.51.2 kg/cm No problem No burr No short circuit Ex. = Example, CEx. =Comparative Example

Scattering: A resin-applied copper foil in a semi-cured state waspunched out with a die, and end surfaces thereof were visually observed.

Examples 69-83

In each of Examples 69 to 83, one of the same resin compositionvarnishes as those obtained in Resin Composition Preparation Examples 16to 30 was applied to one surface of a 18 μm thick copper foil so as toform a dry adhesive layer having a thickness of 60 μm, and in each ofExamples 84 to 87, one of the same resin composition varnishes as thoseobtained in Resin Composition Preparation Examples 34 to 37 was appliedto one surface of a 18 μm thick copper foil so as to form a dry adhesivelayer having a thickness of 60 μm. The copper foils having the adhesivelayer each were dried in a hot air circulating dryer at 140° C. for 5minutes, to obtain resin-applied copper foils which are included in thecircuit laminate material of the present invention. When theresin-applied copper foils were cut with a knife, they was free fromcracking and scattering of a resin in the vicinity of cut portions, sothat they were excellent in handling properties.

In each Example, separately, 100 parts by weight of an aromaticpolyester non-woven fabric (thickness 0.1 mm, supplied by Kuraray Ltd.)was impregnated with 120 parts by weight, as a solid content, of theresin composition varnish obtained in one of the above Resin CompositionPreparation Examples, the impregnated non-woven fabric was dried in ahot air circulating dryer at 140° C. for 5 minutes to obtain prepreg.Four sheets of the prepreg were stacked one on another, and 18 μm thickcopper foils were placed on the outermost surfaces of the laminate, onecopper foil on one surface and the other copper foil on the othersurface. The resultant set was shaped under a pressure of 20 kg/cm²under heating conditions of 200° C., to give a double-side copper-cladlaminate having a thickness of 0.4 mm. Further, surfaces of thedouble-side copper-clad laminate were etched in portions requiring nocopper foil, to obtain an inner-layer circuit board.

In each Example, then, the above resin-applied copper foils were stackedon both the surfaces of the inner-layer circuit board such that theresin surface of each resin-applied copper foil was attached to eachinner-layer circuit. Then, the resultant set was shaped under a pressureof 20 kg/cm² under heating conditions of 200° C. for 2 hours, to obtainan inner-layer-circuit-possessing multi-layered copper-clad laminate.The so-obtained laminates were measured or tested in the same manner asin Example 52. Table 4 shows the results.

Example 88

An inner-layer-possessing multi-layered metal-clad laminate was obtainedin the same manner as in Example 70 except that the resin varnishobtained in Resin Composition Preparation Example 17 was used and thatthe 18 μm thick copper foils were replaced with 18 μm thick 42 alloyfoils. The laminate was measured or tested in the same manner as inExample 52. Table 4 shows the results.

Example 89

The resin composition varnish obtained in Resin Composition PreparationExample 17 was applied to one surface of a 38 μm thick polyethyleneterephthalate film treated so as to be peeled off, such that a dryadhesive layer having a thickness of 60 μm was to be formed, and thefilm having the adhesive layer was dried in a hot air circulating dryerat 140° C. for 5 minutes, to obtain an adhesive film. When the adhesivefilm was cut with a knife, it was free from cracking and scattering of aresin in the vicinity of cut portions, so that it was excellent inhandling properties. Then, a 18 μm thick copper foil was attached to theadhesive surface of the adhesive film, to obtain a resin-applied copperfoil which is included in the circuit laminate material of the presentinvention. In this manner, a plurality of resin-applied copper foilswere prepared.

Separately, 100 parts by weight of an aromatic polyester non-wovenfabric (thickness 0.1 mm, supplied by Kuraray Ltd.) was impregnated with120 parts by weight, as a solid content, of the resin compositionvarnish obtained in Resin Composition Preparation Example 17, theimpregnated non-woven fabric was dried in a drying furnace at 140° C.for 5 minutes to obtain prepreg. Four sheets of the prepreg were stackedone on another, and 18 μm thick copper foils were placed on theoutermost surfaces of the laminate, one copper foil on one surface andthe other copper foil on the other surface. The resultant set was shapedunder a pressure of 20 kg/cm² under heating conditions of 200° C., togive a double-side copper-clad laminate having a thickness of 0.4 mm.Further, surfaces of the double-side copper-clad laminate were etched inportions requiring no copper foil, to obtain an inner-layer circuitboard.

Then, the above resin-applied copper foils were stacked on both thesurfaces of the inner-layer circuit board such that the resin surface ofeach resin-applied copper foil was attached to inner-layer circuits.Then, the resultant set was shaped under a pressure of 20 kg/cm² underheating conditions of 200° C. for 2 hours, to obtain aninner-layer-circuit-possessing multi-layered copper-clad laminate. Thelaminate was measured or tested in the same manner as in Example 52.Table 4 shows the results.

Comparative Example 9

100 Parts by weight of the same siloxane-modified polyimide resin asthat obtained in Synthesis Example 3 and 400 parts by weight of thecompound of the formula (4-2) were added to tetrahydrofuan and fullymixed and dissolved to obtain a resin composition having a solid contentof 30% by weight. Then, the resin composition was used to prepare aninner-layer-circuit-possessing copper-clad laminate in the same manneras in Examples 69. The laminate was measured or tested in the samemanner as in Example 52. Table 3 shows the results.

Comparative Example 9

179 Parts by weight of the compound of the formula (4-2) and 168 partsby weight of the compound of the formula (1A) in which R was methyl(methylallyl groups had a mole equivalent of 1.0 per mole equivalent ofmaleimide groups) were added to tetrahydrofuan and fully mixed anddissolved to obtain a resin composition having a solid content of 30% byweight. Then, the resin composition was used to prepare aninner-layer-circuit-possessing copper-clad laminate in the same manneras in Example 69. The laminate was measured or tested in the same manneras in Example 52. Table 4 shows the results.

Comparative Example 10

A resin composition varnish was obtained in the same manner as in ResinComposition Preparation Example 16 except that the siloxane-modifiedpolyimide obtained in Synthesis Example 3 was replaced with anacrylonitrile-butadiene copolymer. Then, the resin composition varnishwas used to prepare an inner-layer-circuit-possessing copper-cladlaminate in the same manner as in Example 69. The laminate was measuredor tested in the same manner as in Example 52. Table 3 shows theresults.

TABLE 4 Properties Heat resistance Dielectric Peel against constantstrength soldering Scattering PCBT Ex. 69 2.9 1.3 kg/cm No problem Noburr No short circuit Ex. 70 2.8 1.2 kg/cm No problem No burr No shortcircuit Ex. 71 2.9 1.3 kg/cm No problem No burr No short circuit Ex. 722.9 1.2 kg/cm No problem No burr No short circuit Ex. 73 3.0 1.2 kg/cmNo problem No burr No short circuit Ex. 74 3.0 1.3 kg/cm No problem Noburr No short circuit Ex. 75 3.0 1.3 kg/cm No problem No burr No shortcircuit Ex. 76 2.8 1.3 kg/cm No problem No burr No short circuit Ex. 772.9 1.2 kg/cm No problem No burr No short circuit Ex. 78 2.8 1.2 kg/cmNo problem No burr No short circuit Ex. 79 2.9 1.2 kg/cm No problem Noburr No short circuit Ex. 80 2.8 1.2 kg/cm No problem No burr No shortcircuit Ex. 81 3.0 1.3 kg/cm No problem No burr No short circuit Ex. 822.9 1.3 kg/cm No problem No burr No short circuit Ex. 83 2.8 1.2 kg/cmNo problem No burr No short circuit Ex. 84 2.9 1.4 kg/cm No problem Noburr No short circuit Ex. 85 3.0 1.4 kg/cm No problem No burr No shortcircuit Ex. 86 3.0 1.4 kg/cm No problem No burr No short circuit Ex. 872.9 1.3 kg/cm No problem No burr No short circuit Ex. 88 2.9 1.2 kg/cmNo problem No burr No short circuit Ex. 89 2.8 1.3 kg/cm No problem Noburr No short circuit CEx. 8 3.3 1.4 kg/cm Copper foil No burr No shortswollen circuit CEx. 9 2.8 1.3 kg/cm No problem Burr No short circuitCEx. 3.5 1.2 kg/cm No problem No burr No short 10 circuit Ex. = Example,CEx. = Comparative Example

What is claimed is:
 1. A thermosetting resin low-dielectric compositioncomprising a component (a): siloxane-modified polyimide, component (b):a compound containing 2 methylallyl groups and having the followingformula (1) or a compound containing 3 allyl groups or 3 methylallylgroups and having the following formula (1A), and component (c): acompound containing at least 2 maleimide groups

wherein R is a hydrogen atom or methyl group.
 2. A thermosettinglow-dielectric resin composition according to claim 1, wherein thecomponents (b) and (c) has a total content of 10 to 900 parts by weightper 100 parts by weight of the component (a) and methylallyl or allylgroups of the component (b) have a mole equivalent of 0.1 to 2.0 permole equivalent of maleimide groups of the component (c).
 3. Athermosetting low-dielectric resin composition according to claim 1,wherein the siloxane-modified polyimide as a component (a) contains 90to 40 mol % of at least one of structural units of the following formula(2a) and 10 to 60 mol % of at least one of structural units of thefollowing formula (2b) when the component (b) is the compound of theformula (1).

wherein X is a tetravalent aromatic group and is any one of a3,3′,4,4′-diphenylsulfone structure, a 3,3′,4,4′-biphenyl structure and2,3′,3,4′-biphenyl structure, Ar is a divalent group selected fromaromatic-ring-possessing groups of the following formula (3), R is—CH₂OC₆H₄— whose methylen group is bonded to Si or an alkylene grouphaving 1 to 10 carbon atoms, and n is an integer of 1 to 20,

 wherein each of R₁, R₂, R₃ and R₄ is independently a hydrogen atom oran alkyl or alkoxy group having 1 to 4 carbon atoms provided that all ofthese are hydrogen atoms in no case.
 4. A thermosetting low-dielectricresin composition according to claim 1, wherein the siloxane-modifiedpolyimide as a component (a) contains 90 to 40 mol % of at least one ofstructural units of the following formula (2a′) and 10 to 60 mol % ofstructural units of the following formula (2b′) when the component (b)has the formula (1A)

wherein X is a direct bond or any one of binding groups of —O—, —SO₂—,—CO—, —C(CH₃)₂—, —C(CF₃)₂— and —COOCH₂CH₂OCO—, Ar is a divalent groupselected from aromatic-ring-possessing groups of the following formula(3A), R is —CH₂OC₆H₄— whose methylen group is bonded to Si or analkylene group having 1 to 10 carbon atoms, and n is an integer of 1 to20,

 wherein each of R₁, R₂, R₃ and R₄ is independently a hydrogen atom oran alkyl or alkoxy group having 1 to 4 carbon atoms provided that all ofthese are hydrogen atoms in no case.
 5. A thermosetting low-dielectricresin composition includes an embodiment in which the siloxane-modifiedpolyimide as a component (a) contains 90 to 40 mol % of at least one ofstructural units of the following formula (2a) and 10 to 60 mol % ofstructural units of the following formula (2b) when the component (b)has the formula (1A)

wherein X is a tetravalent aromatic group and is any one of a3,3′,4,4′-diphenylsulfone structure, a 3,3′,4,4′-biphenyl structure and2,3′,3,4′-biphenyl structure, Ar is a divalent group selected fromaromatic-ring-possessing groups of the following formula (3A) recitedclaim 4, R is —CH₂OC₆H₄— whose methylen group is bonded to Si or analkylene group having 1 to 10 carbon atoms, and n is an integer of 1 to20.
 6. A thermosetting low-dielectric resin composition according toclaim 1, wherein the siloxane-modified polyimide as component (a) has adielectric constant of 3.0 or less.
 7. A thermosetting low-dielectricresin composition according to claim 1, wherein the siloxane-modifiedpolyimide as component (a) has a glass transition temperature of 150° C.or lower.
 8. A thermosetting low-dielectric resin composition accordingto claim 1, wherein the siloxane-modified polyimide as component (a) hasa weight average molecular weight of 5,000 to 500,000.
 9. Athermosetting low-dielectric resin composition according to claim 1,wherein the compound containing at least 2 maleimide groups as component(c) is a compound of the formula (4-1) to (4-5):

wherein p is an integer of 0 to 8;


10. A thermosetting low-dielectric resin composition according to claim1, which contains 5 to 70% by weight, based on the total solid content,of a filler having an average particle diameter of 1 μm or less.
 11. Athermosetting low-dielectric resin composition according to claim 1,which has a dielectric constant of 3.2 or less after cured.